由于工作失误，他被降职为普通职员。

He was demoted to a regular clerk due to his mistake at work.

demoted 是动词 demote 的过去式，由前缀 de-（表示"向下、降低"）和词根 mote（来自拉丁语 movere，意为"移动"）组成。demote 字面意思是"使向下移动"，引申为"降职、降低职位"。